major cities had more than one BBS running on TRS-80, Apple II, Atari, IBM PC, Commodore 64, Sinclair, and similar personal computers. The IBM PC was introduced in 1981, and subsequent models of both Mac computers and PCs were used throughout the 1980s. Multiple modems, followed by specialized telecommunication hardware, allowed many users to be online simultaneously. Compuserve, Prodigy, and AOL were three of the largest BBS companies and were the first to migrate to the Internet in the 1990s. Between the mid-1980s and the mid-1990s, BBSes numbered in the tens of thousands in North America alone. Message forums (a specific structure of social media) arose with the BBS phenomenon throughout the 1980s and early 1990s. When the World Wide Web (WWW, or 'the web') was added to the Internet in the mid-1990s, message forums migrated to the web, becoming Internet forums, primarily due to cheaper per-person access as well as the ability to handle far more people simultaneously than telco modem banks. Digital imaging and semiconductor image sensor technology facilitated the development and rise of social media. Advances in metal–oxide–semiconductor (MOS) semiconductor device fabrication, reaching smaller micron and then sub-micron levels during the 1980s1990s, led to the development of the NMOS (n-type MOS) active-pixel sensor (APS) at Olympus in 1985, and then the complementary MOS (CMOS) active-pixel sensor (CMOS sensor) at NASA's Jet Propulsion Laboratory (JPL) in 1993. CMOS sensors enabled the mass proliferation of digital cameras and camera phones, which bolstered the rise of social media. Development of social-media platforms In 1991, when Tim Berners-Lee integrated hypertext software with the Internet, he created the World Wide Web, marking the beginning of the modern era of networked communication. This breakthrough facilitated the formation of online communities and enabled support for offline groups through the use of weblogs, list servers, and email services. The evolution of online services progressed from serving as channels for networked communication to becoming interactive platforms for networked social interaction with the advent of Web 2.0. The roots of social media can be traced back to the mid-1990s with the advent of platforms like GeoCities, Classmates.com, and SixDegrees.com. While instant messaging and chat clients existed at the time, SixDegrees was unique as it was the first online service designed for real people to connect using their actual names. It boasted features like profiles, friends lists, and school affiliations, making it "the very first social networking site"